For anyone still trying to sort Derrida out, here's a hopefully helpful attempt at explication from Rick Roderick. I liked Roderick's approach in directly opposing Derrida's theory to the "Theory of Reference." This is an allusion to Gottlob Frege, who was discussed in an earlier PEL episode.
I found it impossible to follow Roderick's argument toward the end of the lecture, until I tracked down the Derrida essay to which he was referring, White Mythology: Metaphor in the Text of Philosophy. (After you open the online PDF file, do an on-screen text search for "The breath is seated," and you'll find the relevant passage.)